In certain phases of flight (ascent, descent, etc.), atmospheric conditions known as “icing” may be encountered if the ambient temperature becomes lower or equal to zero degrees Celsius. These conditions can lead to deposits of ice on certain parts of the engine, particularly on the flow separator. The flow separator is an instrument that makes it possible to split the air admitted into the engine into a primary flow and a secondary flow. It is particularly adapted to cooperate with a downstream guide vane bringing the flow of air into the axis of the engine.
Among the de-icing systems known from the prior art, three main categories of systems may be distinguished: pneumatic de-icing systems, electrical de-icing systems, and oil circulation de-icing systems. In pneumatic de-icing systems, one takes air that has been compressed, and thus heated, from a high pressure compressor. This air is injected near to the parts of the engine to be de-iced. The principle consists in guaranteeing a sufficiently high temperature on the zone to be de-iced so as to prevent the formation of ice.
A device for de-icing a separator by a system of notches is known. A separator 100 of a turbine engine 101 cooperating with a downstream guide vane 102 is illustrated in FIGS. 1 and 2 along a sectional view.
The device comprises:                a plurality of upper grooves 103 spread out circumferentially and machined in an upper zone 104 of the downstream guide vane 102, parallel to the engine axis X. An upper groove 103 is represented in perspective in FIG. 3,        a plurality of lower notches 105 spread out circumferentially and machined in the separator 100, orthogonally to the engine axis X.        
It may be noted that the upper grooves 103 and the lower notches 105 belong to different planes: they are offset angularly with respect to each other.
The upper zone 104 of the downstream guide vane 102 is subjected to air flows 106 at high temperature coming from injectors (not represented). Each air flow 106 is guided via an upper groove 103 to a circular wall 107 of the separator 100. Since the upper grooves 103 are parallel to the engine axis X, the wall 107 is impacted orthogonally by the air flow 106. Each air flow 106 is thus substantially divided into two semi-flows of air 108 during the impact on the wall 107.
The semi-flows of air 108 then circulate along the wall 107 in azimuthal directions through the axial clearance between the wall 107 and the downstream guide vane 102. Finally, the semi-flows of air 108 are evacuated from the separator 100 via the lower notches 105. The upper grooves 103 and lower notches 105 thereby participate in an air flow circuit heating the wall 107 thereby enabling its de-icing.
This device nevertheless has a drawback. The thermal profile of the separator is saw tooth like, in particular when its thermal conductivity is low, for example for a titanium separator. In fact, since the grooves through which the hot air passes are spread out circumferentially, the thermal profile exhibits temperature peaks at the level of the grooves, and temperature wells between two grooves. A conventional profile is illustrated in FIG. 4, representing the temperature T of the tip 109 of the separator 100 on a portion situated between two upper grooves 103, in a case of conventional dimensioning in icing conditions.
To minimise temperature wells, a solution consists in increasing the air flow rate. However, this solution involves constraints at the level of the distribution system and leads to a loss of consumption. Another solution consists in reducing the section of the clearance between grooves. However, this reduction is restricted by the limits of the tooling.